High-thermal-conductivity low-dielectric organic silica gel as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic silicon materials, and discloses high-thermal-conductivity low-dielectric organic silica gel and a preparation method and application thereof.The high-thermal-conductivity low-dielectric organic silica gel is prepared from a component A and a component B. The component A is prepared from, by weight, 35-45 parts of vinyl polysiloxane, 40-50 parts of vinyl silicone resin, 5-20 parts of modified boron nitride, 0.75-1.25 parts of a flatting agent, 1.5-2.5 parts of a defoaming agent and 0.05-0.15 part of a platinum catalyst; and the component B comprises the following components in parts by weight: 15-20 parts of vinyl polysiloxane, 60-85 parts of hydrogen-containing silicone oil and 0.05-0.15 part of an inhibitor. According to the scheme, a continuous and effective 3D heat conduction network is constructed through modified boron nitride, the heat conduction performance of the organic silica gel is improved, meanwhile, covalent interaction is formed between the modified boron nitride and other matrixes, interface bonding is high, the dipole polarization effect at an interface is reduced, the dielectric constant is reduced, and the organic silica gel is quite suitable for the field of electronic packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of organic silicon materials, and in particular to an organic silicon with high thermal conductivity and low dielectric constant, and a preparation method and application thereof. Background Art

[0002] With the miniaturization and increasing efficiency of electronic devices, the use of thermally conductive materials has become increasingly important. However, these materials face numerous challenges, such as low thermal conductivity and poor thermal stability. If heat is not dissipated promptly, product efficacy and lifespan will be reduced. Similarly, poor thermal stability can also shorten product lifespan and even cause safety incidents. Patent CN112659578B proposes a low-dielectric-constant, high-thermal-conductivity silicone sheet with a thermal conductivity exceeding 3 W / (m·K), but the boron nitride content is 45%-73%, resulting in relatively poor shear strength. Patent CN116515454A proposes a two-component, high-thermal-conductivity, low-dielectric-constant silicone potting compound with a dielectric constant of less than 3.0 (tested at 100 Hz) and a thermal conductivity of greater than 1.5 W / (m·K). Similarly, the addition of a larger amount of powder results in poor shear strength. To address these issues, developing a highly efficient, stable, and shear-strength thermally conductive silicone is of great significance. Summary of the Invention

[0003] To achieve excellent thermal conductivity, good thermal stability, and a low dielectric constant for organic silica gel, the present invention provides a high-thermal-conductivity, low-dielectric organic silica gel, and its preparation method and application. The raw materials include components A and B. Component A comprises, by weight, 35-45 parts vinyl polysiloxane, 40-50 parts vinyl silicone resin, 5-20 parts modified boron nitride, 0.75-1.25 parts leveling agent, 1.5-2.5 parts defoamer, and 0.05-0.15 parts platinum catalyst; and component B comprises, by weight, 15-20 parts vinyl polysiloxane, 60-85 parts hydrogenated silicone oil, and 0.05-0.15 parts inhibitor. This solution constructs a continuous and effective 3D thermal conductive network through modified boron nitride, improving the thermal conductivity of the organic silica gel. At the same time, the modified boron nitride forms a covalent interaction with the other matrix, resulting in a strong interfacial bond, reducing dipole polarization at the interface and lowering the dielectric constant, making the organic silica gel of the present invention very suitable for the field of electronic packaging.

[0004] The specific technical solutions of the present invention are as follows: A high thermal conductivity and low dielectric organic silicone comprises a component A and a component B, wherein the weight ratio of component A to component B is (5-9):1; more preferably, the weight ratio of component A to component B is (5-7):1; Under the above optimized ratio, the properties of the base polymer reach the best balance, ensuring sufficient and moderate curing to form a network structure with an ideal cross-linking density.

[0005] Wherein, component A comprises, by weight, 35-45 parts of vinyl polysiloxane, 40-50 parts of vinyl silicone resin, 5-20 parts of modified boron nitride, 0.75-1.25 parts of leveling agent, 1.5-2.5 parts of defoaming agent, and 0.05-0.15 parts of platinum catalyst; Component B comprises, by weight, 15-20 parts of vinyl polysiloxane, 60-85 parts of hydrogenated silicone oil, and 0.05-0.15 parts of an inhibitor.

[0006] Furthermore, the vinyl polysiloxane in component A is one or more combinations of vinyl-terminated dimethyl polysiloxane, vinyl-terminated dimethyl vinyl polysiloxane, and methyl-terminated polyvinyl methyl dimethyl siloxane; wherein the vinyl content is 0.4 wt%-0.8 wt%.

[0007] The vinyl silicone resin has an R / Si value of 1.5-2 and a vinyl content of 3 wt %-5 wt %.

[0008] The modified boron nitride is modified to convert the hydrophilic surface of the boron nitride into an organophilic surface, thereby preventing its agglomeration and rapid thickening in the rubber compound, improving its wettability with vinyl polysiloxane and resin, and achieving a strong bond with the vinyl polysiloxane and resin; the modified boron nitride is nanometer-level, preferably with a particle size of 30-200nm, and more preferably, the boron nitride particle size is one of the above or a combination of two.

[0009] In a specific embodiment of the present application, boron nitride powders with a particle size of 150 nm and 30 nm are preferably used for modification. In specific applications, the boron nitride particles with a particle size of 150 nm account for 20% of the total amount used, and the boron nitride particles with a particle size of 30 nm account for 80% of the total amount used. Of course, different proportions within the above particle size ranges can be selected and used according to specific application requirements.

[0010] Preferably, the preparation method of modified boron nitride in this application comprises the following specific steps: Surface activation: Grind boron nitride in a ball mill in hydrogen peroxide medium for 4-8 hours, then centrifuge to separate the boron nitride powder, and place the centrifuged powder in a vacuum drying oven for vacuum drying; The amount of hydrogen peroxide used is 15-20 times the weight of boron nitride, and the mass concentration of hydrogen peroxide is 30%.

[0011] Silane grafting: Prepare an 80-95% by volume ethanol aqueous solution, dropwise add a silane coupling agent into the ethanol solution, and continuously stir and mix until uniform. The amount of the silane coupling agent is 0.5-2 wt% of the powdered boron nitride. Then, dropwise add acetic acid to adjust the pH of the solution to 4.5-5.5. Add the powdered boron nitride to the above solution and ultrasonically stir. Then, transfer the solution to an oil bath at 60°C-80°C and continuously stir for reaction. Nitrogen protection is used during the reaction, and the reaction time is 2-4 hours. After the reaction, the solution is filtered under reduced pressure and washed with deionized water and ethanol. Finally, the product is dried in a vacuum oven to obtain modified boron nitride.

[0012] The silane coupling agent is one of vinyltrimethoxysilane, KH550 and KH570, and the concentration of the ethanol aqueous solution is 80-95%.

[0013] This modification method replaces the strong acid used in existing technologies with hydrogen peroxide, reducing the use of hazardous reagents and being environmentally friendly. The acidic environment accelerates the hydrolysis of silane methoxy groups (-OCH3) to silanols (-Si-OH) while inhibiting their self-condensation. The introduction of nitrogen protection reduces the oxidative side reaction of silane at high temperatures (70°C). This also increases the silane grafting rate, improves the dispersion of boron nitride, and provides more crosslinking points, further enhancing the performance of the silicone rubber.

[0014] The leveling agent is a polyether-modified siloxane, specifically selected from any one of SE2135 of Wanhua, IOTA1823 of Iota, and HM668G20 of WACKER, or any mixture thereof.

[0015] The defoaming agent is fumed silica, specifically selected from any one of Evonik's AEROSIL® R 106 and Tokuyama's REOLOSIL® QS-09, or any mixture thereof.

[0016] The platinum catalyst is composed of a carrier and a platinum-containing active component, wherein the carrier is vinyl-terminated dimethylvinylpolysiloxane, the platinum-containing active component is platinum, and the platinum concentration in the platinum catalyst is 4000-6000 ppm, more preferably 5000 ppm.

[0017] Furthermore, in component B, the vinyl silicone resin has an R / Si value of 1.5-2 and a vinyl content of 3 wt %-5 wt %.

[0018] The hydrogen-containing silicone oil is a mixture of one or more of hydrogen-terminated hydrogen-containing silicone oil, end-side hydrogen-containing silicone oil, and side hydrogen-containing silicone oil, and the hydrogen content is between 0.3wt% and 0.8wt%.

[0019] The inhibitor is any one of ethynylcyclohexanol, diallylformamide, tetramethyldivinyldisiloxane, tetramethyltetravinylcyclotetrasiloxane and diallyl maleate, or any mixture thereof.

[0020] The silicon-ethylene bonds at different positions in component A and the silicon-hydrogen bonds at different positions in component B undergo a quantitative, by-product-free addition reaction under platinum catalysis, forming a three-dimensional network with -Si-CC-Si- as the cross-linking point, thereby providing the above-mentioned basic properties of organic silicone. The boron nitride in component A further reacts with the silicon-hydrogen bonds in component B, enters the main polymer network, and becomes part of the structure, thereby improving the interfacial wettability, enhancing the interfacial adhesion, reducing the interfacial thermal resistance, and more effectively improving the thermal conductivity of the silicone.

[0021] In addition, the present invention also provides a method for preparing the above-mentioned high thermal conductivity and low dielectric silicone, which specifically includes the following steps: (1) Preparation of modified boron nitride: Surface activation: Grind boron nitride in a ball mill in hydrogen peroxide medium for 4-8 hours, then centrifuge to separate the boron nitride powder, and place the centrifuged powder in a vacuum drying oven for vacuum drying; The amount of hydrogen peroxide used is 15-20 times the weight of boron nitride, and the mass concentration of hydrogen peroxide is 30%; Silane grafting: Prepare an 80-95% by volume ethanol aqueous solution, add a silane coupling agent dropwise into the ethanol solution and continuously stir and mix until uniformly mixed. The amount of the silane coupling agent is 0.5-2 wt% of the powdered boron nitride. Then, add acetic acid dropwise to adjust the pH of the solution to 4.5-5.5. Add the powdered boron nitride to the above solution and ultrasonically stir for 20 minutes at a frequency of 50 Hz. Then, transfer the solution to an oil bath at 60°C-80°C and continuously stir for reaction. Nitrogen protection is used during the reaction process. The reaction time is 2-4 hours. After the reaction, the solution is filtered under reduced pressure and washed with deionized water and ethanol. Finally, the product is dried in a vacuum oven to obtain modified boron nitride.

[0022] (2) Preparation of component A: Vinyl polysiloxane, vinyl silicone resin, modified nano-boron nitride, leveling agent, defoaming agent, and platinum catalyst are added to a blender in sequence. After the stirring and dispersion process is completed, vacuum is applied until there are no bubbles, thereby obtaining component A. (3) Preparation of component B: Vinyl polysiloxane, hydrogenated silicone oil, and inhibitor are sequentially added to a blender. After the stirring and dispersion process is completed, vacuum is applied until there are no bubbles, thereby obtaining component B. (4) The above components A and B are mixed evenly in proportion, vacuum degassed, and cured to obtain an organic silicone with high thermal conductivity and low dielectric properties.

[0023] In step (2), the mixer is a planetary mixer, the stirring process is 70-120 rpm for 60-100 minutes, and the dispersion process is 1500-2500 rpm for 60-100 minutes.

[0024] In step (3), the stirring process is 70-120 rpm for 50-100 minutes, and the dispersion process is 1500-2500 rpm for 50-100 minutes.

[0025] The planetary mixer has a dispersion disk and a stirring paddle, so the above-mentioned dispersion and stirring processes can be started at the same time without interfering with each other.

[0026] In step (4), the curing condition is 120°C for 30 minutes.

[0027] The organic silica gel obtained above can be applied to IGBT modules of new energy vehicles to potting and protect chips, disperse thermal stress, and isolate moisture and dust.

[0028] Compared with the prior art, the high thermal conductivity and low dielectric silicone provided by the present invention has the following beneficial effects: (1) Modified boron nitride is added to the organic silica gel described in the present invention, which improves the thermal conductivity of the system glue, reduces the dielectric constant of the system glue, reduces parasitic capacitance to avoid current surge and electromagnetic interference at the moment of switching; suppresses signal loss, and to a certain extent avoids signal delay and distortion; improves insulation reliability, extends service life, and makes it more suitable for electronic packaging; the surface of the modified boron nitride is grafted with active groups through a silane coupling agent to form a chemical bond with vinyl polysiloxane, thereby avoiding filler agglomeration and improving mechanical stability.

[0029] (2) The present invention ensures good processing performance by using different ratios of components A and B, making it better applicable to industrial production. In addition, while improving thermal conductivity, it maintains low density and high insulation, making it suitable for high-frequency and high-heat dissipation scenarios such as 5G communications and IGBT modules, and can maintain stable performance in various harsh environments. DETAILED DESCRIPTION

[0030] The present invention will be further described with reference to the following embodiments. However, the following embodiments are merely preferred embodiments of the present invention and therefore cannot be used to limit the scope of implementation of the present invention. In other words, equivalent changes and modifications made within the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

[0031] The platinum catalyst used in the following examples and comparative examples consists of a carrier and a platinum-containing active component, wherein the carrier is vinyl-terminated dimethylvinylpolysiloxane, the platinum-containing active component is platinum, and the platinum concentration in the platinum catalyst is 5000 ppm.

[0032] The leveling agent is a polyether-modified siloxane, specifically selected from any one of SE2135 of Wanhua, IOTA1823 of Iota, and HM668G20 of WACKER, or any mixture thereof.

[0033] The defoaming agent is fumed silica, specifically selected from any one of Evonik's AEROSIL® R 106 and Tokuyama's REOLOSIL® QS-09, or any mixture thereof.

[0034] Example 1 A method for preparing a high thermal conductivity and low dielectric silicone rubber, comprising the following steps: (1) Preparation of modified boron nitride: Surface activation: Grind in a ball mill for 6 hours in a hydrogen peroxide medium, with a ball-to-material ratio of 15:1 and a rotation speed of 400 rpm. After the grinding, centrifuge to separate the boron nitride powder. Place the centrifuged powder in a vacuum drying oven at 60°C and dry it in a vacuum oven for 12 hours. The amount of hydrogen peroxide used is 20 times the weight of the boron nitride, and the mass concentration of hydrogen peroxide is 30%.

[0035] Silane Grafting: Prepare a 90% (volume) ethanol-water solution. Add 0.4g of vinyltrimethoxysilane dropwise to 100ml of the ethanol solution with constant stirring. Then, add acetic acid dropwise to adjust the pH of the solution to approximately 5. Add 30g of boron nitride to the solution and ultrasonically stir for 20 minutes at 50Hz. Then, transfer to an oil bath and react at 70°C with constant stirring for 4 hours. N2 protection is used during the reaction.

[0036] The solution after the reaction was filtered under reduced pressure and washed with deionized water and ethanol 2-3 times. The product was placed in a vacuum oven at 70° C. and dried for 12 hours to obtain modified boron nitride.

[0037] Boron nitride powders with an average particle size of 30 nm and 150 nm were respectively subjected to the above modification, and then mixed in a ratio of 20% of the total amount of boron nitride with a particle size of 150 nm and 80% of the total amount of boron nitride with a particle size of 30 nm, and 29.3 parts of them were taken for standby use.

[0038] (2) Preparation of component A: 36.036 parts of vinyl polysiloxane (vinyl content of 0.41 wt%, vinyl-terminated dimethyl vinyl polysiloxane), 43.214 parts of vinyl silicone resin (R / Si value of 1.83, vinyl content of 2.7 wt%), 18 parts of modified nano-boron nitride, 0.85 parts of polyether-modified siloxane, 1.8 parts of fumed silica, and 0.1 parts of platinum catalyst were added to a double planetary mixer in sequence, stirred at 100 rpm for 90 minutes, and dispersed at 2200 rpm for 80 minutes. After the stirring and dispersion process was completed, the mixture was evacuated until there was no bubble, thereby obtaining component A. (3) Preparation of component B: 16 parts of vinyl polysiloxane (vinyl content of 0.41 wt%, vinyl-terminated polydimethylsiloxane), 83.92 parts of hydrogenated silicone oil (side hydrogenated silicone oil, hydrogen content of 0.5 wt%), and 0.08 parts of ethynyl cyclohexanol were added to a double planetary mixer in sequence, stirred at 100 rpm for 60 minutes, and dispersed at 2200 rpm for 50 minutes. After the stirring and dispersion process was completed, the mixture was evacuated until there was no bubble, thereby obtaining component B. (4) The above-mentioned component A and component B are mixed evenly in a weight ratio of 8:1, vacuum degassed, and cured (curing conditions 120°C, 30 minutes) to obtain a high thermal conductivity and low dielectric silicone.

[0039] Example 2 A method for preparing a high thermal conductivity and low dielectric silicone rubber, comprising the following steps: (1) Preparation of modified boron nitride: same as step (1) in Example 1; (2) Preparation of component A: 41.544 parts of vinyl polysiloxane (vinyl content of 0.18%, vinyl-terminated dimethyl polysiloxane and vinyl-terminated dimethyl vinyl polysiloxane), 41.026 parts of vinyl silicone resin (R / Si value of 1.61, vinyl content of 4.5wt%), 15 parts of modified nano-boron nitride, 0.75 parts of polyether-modified siloxane, 1.6 parts of fumed silica, and 0.08 parts of platinum catalyst (same problem) were added into a double planetary mixer in sequence, stirred at 100 rpm for 90 minutes, and dispersed at 2200 rpm for 80 minutes. After the stirring and dispersion process was completed, vacuum was evacuated until there was no bubble, thereby obtaining component A. (3) Preparation of component B: 16.83 parts of vinyl polysiloxane (vinyl content of 0.18%, vinyl-terminated dimethyl polysiloxane and vinyl-terminated dimethyl vinyl polysiloxane), 83.09 parts of hydrogenated silicone oil (end-side hydrogenated silicone oil, hydrogen content of 0.7 wt%), and 0.08 parts of inhibitor (ethynyl cyclohexanol) were added to a double planetary mixer in sequence, stirred at 100 rpm for 60 minutes, and dispersed at 2200 rpm for 50 minutes. After the stirring and dispersion process was completed, vacuum was evacuated until there was no bubble, thereby obtaining component B; (4) The above-mentioned component A and component B are mixed evenly in a weight ratio of 8:1, vacuum degassed, and cured (curing conditions 120°C, 30 minutes) to obtain a high thermal conductivity and low dielectric silicone.

[0040] Comparative Example 1 The preparation method of the organic silica gel provided in this comparative example is substantially the same as that of Example 1, except that the preparation steps of the modified boron nitride in step (1) are: Surface activation: Grind in a ball mill for 6 hours in a hydrogen peroxide medium, with a ball-to-material ratio of 15:1 and a rotation speed of 400 rpm. After the grinding, centrifuge the boron nitride powder and place the centrifuged powder in a vacuum drying oven at 60°C for 12 hours. The amount of hydrogen peroxide used is 20 times the weight of the boron nitride, and the mass concentration of hydrogen peroxide is 30%.

[0041] Silane Grafting: Prepare a 70% (volume) ethanol-water solution and dropwise add 1g of vinyltrimethoxysilane to 100ml of the ethanol solution with constant stirring. Acetic acid is then added to adjust the pH of the solution to approximately 5. Add 30g of boron nitride to the solution and ultrasonically stir at 50Hz for 20 minutes. Then, transfer the solution to an oil bath and react at 90°C with constant stirring for 4 hours under nitrogen protection.

[0042] The solution after the reaction was filtered under reduced pressure and washed 2-3 times with deionized water and ethanol. The product was placed in a vacuum oven at 70° C. and dried for 12 hours to obtain modified boron nitride. The remaining steps were the same as in Example 1.

[0043] Comparative Example 2 The preparation method of the organic silica gel provided in this comparative example is basically the same as that of Example 1, except that the weight ratio of component A to component B is 4:1.

[0044] Comparative Example 3 The preparation method of the organic silica gel provided in this comparative example is basically the same as that of Example 1, except that in step (2), the R / Si value of the vinyl silicone resin in component A is 1.36; and the ratio of component A to component B is 6:1.

[0045] Comparative Example 4 The preparation method of the organic silica gel provided in this comparative example is substantially the same as that of Example 1, except that, in step (2), component A comprises, by weight: 27.716 parts of vinyl polysiloxane (vinyl content of 0.21%, methyl-terminated polyvinyl methyl dimethyl siloxane), 50.384 parts of vinyl silicone resin (R / Si value of 1.83), 18 parts of modified boron nitride, 1.3 parts of polyether-modified siloxane, 2.5 parts of fumed silica, and 0.1 part of platinum catalyst; In the step (3), component B comprises, by weight, 12 parts of vinyl polysiloxane (vinyl content of 0.21%, methyl-terminated polyvinyl methyl dimethyl siloxane), 87.92 parts of side hydrogenated silicone oil, and 0.08 parts of ethynyl cyclohexanol.

[0046] Comparative Example 5 The preparation method of the organic silica gel provided in this comparative example is basically the same as that of Example 1, except that purchased modified boron nitride (Suzhou Napu Material Technology Co., Ltd.) is used.

[0047] Experimental Example: Performance Test of High Thermal Conductivity and Low Dielectricity Organic Silicone Thermal conductivity: measured using a hot disk thermal conductivity tester (25°C) according to ASTM D 5470.

[0048] Dielectric constant: According to standard GB / T 1409-2006, use high and low frequency dielectric constant tester GCSTD-D, frequency 1 MHz, cut into 50mm*50mm*1.5mm sheets, and measure at 25℃.

[0049] Shear strength: The thickness of the prepared sample is 0.2mm and the length is 1cm. The sample is clamped symmetrically on the fixture with a distance of 50mm from the clamping point to the nearest bonding end. The shear force change rate is set between 8.3MPa-9.8MPa per minute.

[0050] Double 85 test: A 2cm long, 2cm wide, 1cm thick adhesive strip is placed in a constant temperature and humidity chamber at 85°C and 85% RH for 1000 hours.

[0051] Table 1 Test items and test standards for high thermal conductivity and low dielectric silicone rubber

[0052] Table 2 Raw material ratios of Examples and Comparative Examples Table 3 Performance test results of the cured adhesives of the examples and comparative examples As can be seen from Table 3, the thermal conductivity of the organic silica gel prepared by the present invention can reach 2.3w / m·K, and the dielectric constant can reach 2.76. In addition, the organic silica gel is subjected to the "double 85" test. After 1000 hours of testing, its internal microstructure has not changed, and its thermal conductivity and flexibility have not changed. It has the outstanding characteristic of long-term maintenance of key properties.

[0053] As can be seen from Example 1 and Comparative Example 1, the thermal conductivity of Comparative Example 1 is lower than that of Example 1. This is because the reaction conditions during the modification of the boron nitride in Comparative Example 1 changed, resulting in incomplete grafting. Although it can form a chemical bond with the hydrogenated silicone oil and become part of the structure, the effect is not as good as that of Example 1. The thermal conductivity and dielectric constant of Comparative Example 5 are similar to those of Comparative Example 1. It can be seen that while conventional existing modified boron nitride has some effect, it is still inferior to the modified boron nitride prepared in the examples. The surface of the modified boron nitride in Example 1 is grafted with active groups via a silane coupling agent. The active vinyl groups react with the hydrogenated silicone oil and become part of the main structure, achieving a strong interfacial bond between the filler and the organosilicon matrix, preventing filler agglomeration, and improving mechanical stability.

[0054] In Comparative Example 2, the ratio of components A and B was altered, resulting in incomplete reaction between the components and an incomplete three-dimensional thermal network, which affected other properties. Similarly, in Comparative Example 4, the raw materials in components A and B were not optimally proportioned, and the three-dimensional thermal network could not be synergistically established, which affected various properties.

[0055] The R / Si of the vinyl silicone resin in Comparative Example 3 changed and was lower than that in Examples 1 and 2, resulting in insufficient crosslinking points and incomplete reaction, which affected various properties of the final silicone product.

[0056] The organic silica gel obtained by the present invention can be applied to IGBT modules for new energy vehicles to encapsulate and protect chips, disperse thermal stress, and isolate moisture and dust. The following should be noted during specific applications: (1) After mixing components A and B, vacuum degassing should be performed for ≥15 minutes to eliminate bubbles, as residual bubbles will reduce insulation strength. (2) During packaging, needle injection or bottom filling should be used in a vacuum environment, with a flow rate controlled at 5-10 g / s. At the same time, the module should be tilted (15°-30°) to allow the colloid to penetrate from the bottom up to avoid residual air gaps.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent replacement, modification, etc. made by technicians in this field without any creative work within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high thermal conductivity and low dielectric organic silicone, characterized in that: Comprising component A and component B, with a weight ratio of component A: component B = (5-9):1; The component A comprises, by weight, 35-45 parts of vinyl polysiloxane, 40-50 parts of vinyl silicone resin, 5-20 parts of modified boron nitride, 0.75-1.25 parts of leveling agent, 1.5-2.5 parts of defoaming agent, and 0.05-0.15 parts of platinum catalyst; The component B comprises, by weight, 15-20 parts of vinyl polysiloxane, 60-85 parts of hydrogenated silicone oil, and 0.05-0.15 parts of an inhibitor.

2. The high thermal conductivity and low dielectric silicone according to claim 1, characterized in that: The preparation method of the modified boron nitride comprises the following specific steps: Surface activation: Grind boron nitride in a ball mill in hydrogen peroxide medium for 4-8 hours, then centrifuge to separate the boron nitride powder, and place the centrifuged powder in a vacuum drying oven for vacuum drying; The amount of hydrogen peroxide used is 15-20 times the weight of boron nitride, and the mass concentration of hydrogen peroxide is 30%; Silane grafting: Prepare an 80-95% by volume ethanol aqueous solution, dropwise add a silane coupling agent into the ethanol solution, and continuously stir and mix until uniform. The amount of the silane coupling agent is 0.5-2 wt% of the powdered boron nitride. Then, dropwise add acetic acid to adjust the pH of the solution to 4.5-5.

5. Add the powdered boron nitride to the above solution and ultrasonically stir. Then, transfer the solution to an oil bath at 60°C-80°C and continuously stir for reaction. Nitrogen protection is used during the reaction, and the reaction time is 2-4 hours. After the reaction, the solution is filtered under reduced pressure and washed with deionized water and ethanol. Finally, the product is dried in a vacuum oven to obtain modified boron nitride.

3. The high thermal conductivity and low dielectric silicone according to claim 1, characterized in that: By weight ratio, component A: component B = (5-7):

1.

4. The high thermal conductivity and low dielectric silicone according to claim 1, characterized in that: The vinyl polysiloxane in component A is one or more of vinyl-terminated dimethyl polysiloxane, vinyl-terminated dimethyl vinyl polysiloxane, and methyl-terminated polyvinyl methyl dimethyl siloxane; the vinyl content thereof is 0.4wt%-0.8wt%; the R / Si value of the vinyl silicone resin is 1.5-2, and the vinyl content is 3wt%-5wt%.

5. The high thermal conductivity and low dielectric silicone according to claim 1, characterized in that: The vinyl silicone resin in component B has an R / Si value of 1.5-2 and a vinyl content of 3wt%-5wt%; the hydrogen-containing silicone oil is a mixture of one or more of hydrogen-terminated hydrogen-containing silicone oil, end-side hydrogen-containing hydrogen-containing silicone oil, and side hydrogen-containing silicone oil, and the hydrogen content is between 0.3wt%-0.8wt%; the inhibitor is any one of ethynylcyclohexanol, diallylformamide, tetramethyldivinyldisiloxane, tetramethyltetravinylcyclotetrasiloxane and diallyl maleate, or any mixture thereof.

6. The method for preparing the high thermal conductivity and low dielectric silicone according to claim 1, characterized in that: The following steps are involved: (1) Preparation of modified boron nitride: Surface activation: Grind boron nitride in a ball mill in hydrogen peroxide medium for 4-8 hours, then centrifuge to separate the boron nitride powder, and place the centrifuged powder in a vacuum drying oven for vacuum drying; The amount of hydrogen peroxide used is 15-20 times the weight of boron nitride, and the mass concentration of hydrogen peroxide is 30%; Silane grafting: Prepare an 80-95% by volume ethanol-water solution, dropwise add a silane coupling agent into the ethanol solution and continuously stir and mix until uniform, the amount of silane coupling agent used being 0.5-2wt% of the powdered boron nitride, then dropwise add acetic acid to adjust the pH of the solution to 4.5-5.5; add the powdered boron nitride to the above solution and ultrasonically stir, then transfer to an oil bath and continuously stir and react at 60°C-80°C, under nitrogen protection during the reaction, for 2-4 hours; after the reaction, filter the solution under reduced pressure and wash with deionized water and ethanol, and finally dry the product in a vacuum oven to obtain modified boron nitride; (2) Preparation of component A: Vinyl polysiloxane, vinyl silicone resin, modified nano-boron nitride, leveling agent, defoaming agent, and platinum catalyst are added to a blender in sequence. After the stirring and dispersion process is completed, vacuum is applied until there are no bubbles, thereby obtaining component A. (3) Preparation of component B: Vinyl polysiloxane, hydrogenated silicone oil, and inhibitor are sequentially added to a blender. After the stirring and dispersion process is completed, vacuum is applied until there are no bubbles, thereby obtaining component B. (4) The above components A and B are mixed evenly in proportion, vacuum degassed, and cured to obtain an organic silicone with high thermal conductivity and low dielectric properties.

7. The method for preparing high thermal conductivity and low dielectric silicone according to claim 6, characterized in that: In step (1), the ball-to-material ratio during grinding is 10-15:1, and the rotation speed is 400-500 rpm; the silane coupling agent is one of vinyltrimethoxysilane, KH550, and KH570.

8. The method for preparing high thermal conductivity and low dielectric silicone according to claim 6, characterized in that: In step (2), the mixer is a planetary mixer, the stirring process is 70-120 rpm for 60-100 minutes, and the dispersion process is 1500-2500 rpm for 60-100 minutes.

9. The method for preparing high thermal conductivity and low dielectric silicone according to claim 6, characterized in that: In step (3), the stirring process is 70-120 rpm for 50-100 minutes, and the dispersion process is 1500-2500 rpm for 50-100 minutes.

10. The method for preparing high thermal conductivity and low dielectric silicone according to claim 6, characterized in that: In step (4), the curing condition is 120°C for 30 minutes.

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